Research in schizophrenia has provided empirical support for the use of self-report inventories for early warning signs of relapse, but to date no published studies have reported on the predictive validity of self-reported early warning signs of relapse in a first-episode cohort. Sixty patients, who had remitted following their first episode of psychosis, participated in a 9-12 month prospective follow-up study. Outcome data on putative prodromal symptoms was available on 46 participants. The Early Signs Scale (ESS) achieved adequate sensitivity but poor specificity and positive predictive validity (PPV) in predicting relapse or symptom exacerbations, although a post hoc increase in the established cut-off significantly improved the outcome. The findings provide qualified support for the use of the ESS in relapse prevention with first-episode patients who are in remission. Further prospective studies with larger numbers of first-episode patients will enable sample sizes enable the comparison of the effectiveness of several prodromal scales using ROC analysis, or a combination of risk factors using regression models.